The present invention relates to an improved computer system and more particularly to an improved computer chip-printed circuit board (PCB) assembly and a method of mounting a chip on a PCB.
The present invention is addressed, in one case, for example, to improving the manner and method in past systems of securing the chip, usually a processor, to the PCB, usually a motherboard, which in certain past systems employed a socket. In this system the socket is mounted on the PCB and then secured thereto by a wave soldering process. The socket is provided with well known pin openings that received corresponding pins mounted in the underneath surface of the chip and by which construction the desired electrical circuits are established and maintained between the two elements.
The employment of a socket in this design creates problems in obtaining an effective and quick way for the proper placement, alignment and spacing of the socket on the PCB. Because of these drawbacks the pins are sometimes bent during their insertion resulting in an unusable assembly. Moreover, in the system employing a socket a special tool in the form of a press is required to seat the chip into the socket. Usually the fastening is accomplished by a "push fit" between the pins of the chip and the openings in the socket.
In addition to the limitations of the present day design employing a socket, its use even when the limitations are controlled within acceptable bounds represent a significant added expense to the manufacturing cost as it relates to the means and method of wave soldering the socket to the PCB and in mounting the chip in the socket.
Both in the use of sockets as described above and in arrangements where the chip is mounted directly on the PCB by wave soldering, similar to that of the present invention, there exist a problem of maintaining the ends of all of the pins that pass through openings in the PCB the same distance from the bottom surface of the PCB and the ends within a common plane parallel to such surface. The failure to do this creates problems during the wave soldering process in obtaining the proper soldering of each pin with the PCB and allows the creation of what is referred to as "solder bridging", where because of the unevenness and slope of the pins during the wave soldering process solder is deposited between adjacent pins resulting in the creation of an objectionable short circuiting condition in the chip.